The monk reached the top, and was throw back down to the ground as fast as he got up there.

Monk, take 21 bludgeoning damage

It is back to the top, and I really think it’s quite unnecessary to throw something else at you. 

Quote from Bluepanther512 >>

Interesting if it's still open.

 I’m afraid you must wait until the next fight to join.

Just as an FYI about Monks...

Slow Fall. Beginning at 4th level, you can use your reaction when you fall to reduce any falling damage you take by an amount equal to five times your monk level.

Vaden backs into the very corner of the arena. His manifested mind moves as well. Then he casts a spell...

fireball

(Vaden is 70 feet from the gnome now, so the gnome will not be able to counterspell this.)
DC 19 Dex save for half, or take 24 fire damage.

Here is the updated map...

updated map

Peren is up now I believe.

Quote from DragonDenn >>

Vaden backs into the very corner of the arena. His manifested mind moves as well. Then he casts a spell...

fireball

(Vaden is 70 feet from the gnome now, so the gnome will not be able to counterspell this.)
DC 19 Dex save for half, or take 24 fire damage.

 DEX: 9, and song of defense to negate the damage.

Peren attacks Hopper three times(Martial arts and extra attack) and moves back 65 feet(Mobile, so no AoO).

Attack: Unable to parse dice roll.-5 Damage: 7

Attack: 13-5 Damage: 10 And I'll use Stunning Strike(DC 16)

Attack: 27-3 Damage: 9

Synaptic Static save: 17

Attack advantage if Stunning Strike works: Attack: 22 Damage: 10(Subtract the original attack's-5 to the roll)

*Editing SS in messed this up, so use the rolls quoted in the post below.*

Quote from Halfastbracegirdle >>

Peren attacks Hopper three times(Martial arts and extra attack) and moves back 65 feet(Mobile, so no AoO).

Attack: 15-5 Damage: 7

Attack: 21-1 Damage: 10

Attack: 20-5 Damage: 6

Synaptic Static save: 12

 Mobile has no effect upon whether or not you take AoE damage. Make the save please.

Quote from Fitz_Coulson >>

Quote from Halfastbracegirdle >>

Peren attacks Hopper three times(Martial arts and extra attack) and moves back 65 feet(Mobile, so no AoO).

Attack: 15-5 Damage: 7

Attack: 21-1 Damage: 10

Attack: 20-5 Damage: 6

Synaptic Static save: 12

 Mobile has no effect upon whether or not you take AoE damage. Make the save please.

That's attack of opportunity.

So it is, my bad! Carry on!

I believe it's the gnome's turn, now?

Quote from Thauraeln_The_Bold >>

Quote from DragonDenn >>

Vaden backs into the very corner of the arena. His manifested mind moves as well. Then he casts a spell...

fireball

(Vaden is 70 feet from the gnome now, so the gnome will not be able to counterspell this.)
DC 19 Dex save for half, or take 24 fire damage.

 DEX: 9, and song of defense to negate the damage.

  So you are spending a 5th level slot to negate the damage?

Quote from DragonDenn >>

Quote from Thauraeln_The_Bold >>

Quote from DragonDenn >>

Vaden backs into the very corner of the arena. His manifested mind moves as well. Then he casts a spell...

fireball

(Vaden is 70 feet from the gnome now, so the gnome will not be able to counterspell this.)
DC 19 Dex save for half, or take 24 fire damage.

 DEX: 9, and song of defense to negate the damage.

  So you are spending a 5th level slot to negate the damage?

 Yep.

Yes then, it is now the gnome's turn.

DM, does Peren need to do some sort of perception check to notice the ball bearings, or can he simply notice them and move around them? I had him do the latter, but wanted to check...

Here is the updated map after the Monk's turn, but prior to the gnome.

Updated map

You can see them,  so either risk walking over them, or just walk around

The gnome will run 35 feet towards Vaden, cast misty step, and attack twice with his rapier (he's now 5 feet away).

*Attack: 12 Damage: 11
Attack: 19 Damage: 13*

Both attacks miss. It is now hoppers turn.

Hopper runs to Peren and attacks.

Hit18 dmg10 (Edit: WOOO CRIT! Extra damage:5)

Hit21 dmg8

extra damage if either hits: 16

(Edit 2:It marked it as manipulated when I added the extra roll for the crit)

(Edit 3: yo wtf the numbers keep changing every time I reload the page)

(Edit 4: Here's the numbers I saw the first time around, I'm using these. Hit: 25 Dmg:6 +3 for crit bonus. Hit: 17 Dmg 11 Sneak attack: 26)